Variable power divider or combiner for radio frequency applications



Nov. 23, 1965 LA VERGNE E. WILLIAMS 3,219,948

VARIABLE POWER DIVIDER 0R COMBINER FOR RADIO FREQUENCY APPLICATIONS Filed Oct. 30. 1961 2 Sheets-sheet 1 24 FIGJ A/vcL E INVENTOR LAVEIZGNE: EMhuJAMs ATTORNEY5 N 23, 1965 LA VERGNE E. WILLIAMS 3,

VARIABLE POWER DIVIDER OR COMBINER FOR RADIO FREQUENCY APPLICATIONS Filed Oct. 50, 1961 2 Sheets-Sheet 2 INVENTOR LAVE26-NE/E. A/\ u. l PMs ATTORNEYS United States Patent 3 219,948 VARIABLE POWER DlVIDER 0R COMBINER FOR RADIO FREQUENCY APPLICATIONS La Vergne E. Williams, Indialantic, Fla, asslgnor to Radiation, Incorporated, Melbourne, Fla., :1 corporation of Florida Filed Oct. 30, 1961, Ser. No. 148,657 14 (Ilaims. (Cl. 333-7) The present invention relates to variable power transmission systems and more particularly to a variable transmission system for controlling the amount of RF. energy transmitted between a common and a plurality of conductors.

A need has arisen to provide an RF. power modulation device for supplying power from one transmission line to a plurality of transmission lines, or vice versa. In order to convert four horn amplitude monopulse antenna feed systems effectively into a conical scan system, it is presently necessary to employ cumbersome devices utilizing lossy, physical contacting elements which introduce variable phase shift between the antennae and feed system. Such a conversion element preferably does not mechanically nutate or rotate; is relatively noise free and is able to produce an electrical scan considerably in excess of any mechanical scanning done by the system.

Also antenna scanners frequently require power division between a common source or receiver and the antennae monitored. To provide an accurate scanner, the irnpedances seen by the generator must remain substantially constant as its output power is shifted from one antenna to another. For example, to scan the radiation pattern of a square tower having a separate antenna located on each of its four sides, it is necessary to cyclically vary the power supplied from a single generator to each individual horn. This is preferably accomplished without employing noisy physically contacting elements or introducing undesirable reactance into the transmission line supplied by the generator.

The present invention provides a system. for variably dividing the RF. power supplied between a common and plurality of other transmission lines by employing a plurality of variable characteristic impedance transmission lines between the common and other lines. The characteristic impedances of the transmission lines are synchronously varied by electromagnetically coupling the ground plane conductor located in proximity to the signal carrying conductors, which make up the transmission line, with a rotating element having at least one conductng element which sequentially changes the signal carrying conductors from a fully loaded to fully unloaded conditlon. To provide faster electrical than mechanical transmission line variation, more than one conducting sector is provided on the rotating element.

For most applications, it is desirable to maintain the distance between the common and parallel lines a quarter wave length long because at this distance, characteristic impedance variations have greatest effect on the input vs. output power characteristic and no reactance terms are introduced. Thereby, constant phase shift is maintained between the common conductor and each of the parallel transmission lines.

In order to maintain the power supplied to a plurality of remote antennae from a transmitter constant, it is necessary to maintain the impedance seen by the transmitter constant. This is accomplished in the present invention by symmetrically arranging the quarter wave length transmission lines so that the impedance seen by the transmitter generator is constant and the sum of the power supplied to the lines is constant.

It accordingly is an object of the present invention to 3,219,948 Patented Nov. 23, 1965 "ice provide a new and improved R.F. variable power coupler for varying the amount of power supplied between one terminal and two or more terminals. It is a further ob ect of the present invention to provide a variable power coupling element for variably dividing power supplied between a single transmission line and a plurality of transmission lines with virtually no attenuation introduced by the element, and by providing constant phase shift between the single and plural transmission lines.

It it a further object of the present invention to provide an element for smoothly varying the power transmitted between one transmission line and a plurality of transmission lines with a minimum of moving parts and no sliding contacts or parts which are subject to frictional wear.

It is an additional object of the present invention to provide a variable power divider wherein the impedance seen by external elements looking into the divider is maintained constant while the power supplied between a common line and each of a plurality of lines is smoothly varied.

It is an additional object of the present invention to provide a power varying element that is capable of use with four horn amplitude monopulse antennae feed systems to convert them effectively to conical scan systems.

Yet an additional object of the present invention is to provide a system for producing conical scan or lobe switching in an antenna system wherein no nutation or rotation of the feed element is necessary; wherein no sliding electrical contacts are employed; wherein the system is easily balanced electrically and has no active or noise producing elements that adversely affect system operation.

It is yet a further object of the present invention to provide a variable power divider between a common terminal and a plurality of output terminals that employs a mechanically rotating element but wherein electrical power distribution is effected at a considerably higher rate than mechanical rotation.

Yet another object of the present invention is to provide a system for varying power supplied between a common transmission line and a plurality of other transmission lines which can smoothly vary the relative amount of power supplied between a number of separate antennaes connected to the other lines and a single transmitter or receiver connected to the common line.

It is a further object of the present invention to provide a new and improved element for enabling plural antennae patterns to be electrically scanned without introducing distortion and noise in the antennae pattern signal coupled to the recorder or readout element.

It is still yet another object of the present invention to provide a new and improved element wherein the relative amount of RF. power supplied to several loads or supplied by several generators to a common load is periodically varied.

Yet an additional object of the present invention is to provide a new and improved system for supplying power between a single and a plurality of transmission lines wherein the amount of power supplied between the lines may be varied at the utilization site of the device.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 of the drawing discloses in exploded perspective one preferred embodiment of the present invention utilizing radially extending transmission lines;

FIGURE 2 is a graph of the variation of driving point conductance (and power) with respect to time in any of the embodiments of FIGURE 1;

FIGURE 3 discloses in exploded perspective another =3 preferred embodiment of the present invention utilizing transmission lines mounted on conical members; and

FIGURE 4 discloses in exploded perspective still another further embodiment of the present invention employing transmission lines mounted on cylindrical members.

FIGURE 1 of the drawings discloses one preferred embodiment of the invention as comprising a metallic ground plane element 11 having four flared slots 12, 13, 14 and 15 radially extending from ground plane center point 16. Disposed in slots 12-15 are signal carrying conductors 17-20, respectively, which are connected together at a point aligned with central point 16. Tapered conductors 17-20 are insulated from block 11 by air in the spaces between them.

The ends of conductors 17-20 remotely located from central point 16, are connected to the interior conductor of coaxial cables 24-27, respectively. The exterior shielded conductors of coaxial cables 24-27 are physically connected to the ground plane element 11 as is the shielded cable of the common coax 28, the interior conductor of which is connected to the common point of the quarter wave length transmission lines 17-20. R.F. energy is thus supplied from coaxial cables 24-27 through the quarter wave length transmission lines to the common coaxial cable 28 or transmission may be effected in the opposite direction.

Disc 22, containing three conducting segments 29, 30 and 31 interspaced between non-conducting segments 32, 33 and 34, is driven at constant frequency by scan motor 36, the rotational velocit yof which is sensed by reference generator 37. Disc 22 rotates in close proximity to ground plane element 11 and the quarter wave length transmission lines 17-20 thereof so that electromagnetic coupling between ground plane 11 and conducting segments 29-31 is effected. Disc 22 is spaced sufficiently close to the planar surface 21 of ground plane block 11 to vary the distributed inductance and capacitance of the quarter-wavelength sections as it is rotated. The characteristic impedance of the conductors 17-20 which make up the quarter wave length transmission lines is accordingly varied as disc 22 is rotated.

When one segment 29 of disc 22 is completely covering the slot 12 in ground plane element 11, the transmission line between cables 24 and 28 which comprises conductor 17 is essentially a quarter wave length shielded transmission line. As the disc 22 is rotated so that nonconducting segment 34 completely covers slot 12, the quarter wave length transformer between coax 24 and 28 is now essentially a two line transmission line with essentially no shielding of conductor 17. Thus, the characteristic impedance of the transmission line between coaxial cables 24 and 28 is minimum when a conducting sector, e.g. 29, is completely covering slot 12 and is maximum when an insulating segment, such as 34, is directly covering slot 12. In this manner it is seen that the characteristic impedance and hence the signal propagated between coaxial cable 24 and 28 is varied merely by rotation of disc 22. As disc 22 rotates from a position where segment 29 completely covers slot 12, to a position where segment 34 completely covers slot 12, the characteristic impedance of the quarter wave length transmission line constituting conductor 17 is smoothly varied from a minimum to maximum value. Similarly, the quarter wave length transmission lines between coaxial cables 25, 26 and 27 and coax 28 are varied to effect power modulation of the energy between the common coax and individual feed cables 25-27.

A plurality of electrically conducting segments 29, 30 and 31 are provided on disc 22 to effect plural power modulation for each quarter wave length transmission line for a single rotation of the shaft of motor 36. Slots 12-15 and conductors 17-20 are flared in radially extending directions so they substantially match the radially extending segments 29-31 of disc 22 and effectuate a maximum to minimum characteristic impedance variation of each quarter wave length transformer or transmission line. It is important to maintain the distance between the point where each of the coaxial cables 24- 27 separately connects with block 11 and the common connection point at a quarter wave length because at this distance there are no reactive terms in the input impedance looking into either end of the transformer. Also, at this distance, variations in characteristic impedance have the greatest effect on the attenuation char acteristic of the quarter wave length line because it has a square law relationship. To maintain constant phase velocity of propagation as disc 22 is rotated, it is important to employ air as the dielectric between conductors 17-20 and disc 22 and block 11.

It is important that the conducting segments 29-31 and conductors 17-20 be positioned so that only one of the segments is maximally electromagnetically coupled to each conductor at a time. Otherwise, the characteristic impedance of the transmission line associated with the conductor does not assume its maximum value and is not smoothly varied. This is accomplished in the embodiment of FIGURE 1 by employing three wedge shaped conducting segments 29-31, having approximately the same size and shape as the four slots 12-15.

FIGURE 2 illustrates by plotting conductance, which is proportional to power, supplied through the transmission lines vs. disc rotation the manner in which the modulation system of FIGURE 1 operates. Sinusoidal graphs 91, 92, 93 and 94 diagrammatically illustrate the fluctuation of power between common coaxial lead 28 and coaxial leads 24, 25, 26 and 2'7 of FIGURE 1 for one and one-quarter electrical revolutions of disc 22 with relation to the quarter wave length transmission line transformers which connect the parallel coaxes with the common coax.

In the graph of FIGURE 2, the abscissa represents the characteristic conductance variation, G, of the transmission lines and the ordinates is indicative of the power transfer between the common and individual transmission lines 24-27, G G G and G being the characteristic conductance variations of the lines in slots 12-15. For purposes of the present discussion it is assumed that a perfect impedance match exists between common coaxial cable 28 and each of the parallel coaxes 24-27 when the quarter wave length conductors are unloaded, that is when insulated segments 32, 33 and 34 are proximate to slots 12-15.

Initially, therefore, it is assumed segment 33 completely covers slot 12 so that the conductor 17 located therein is completely unloaded and maximum transfer is effected between coaxes 24 and 28. This is illustrated on FIGURE 2 wherein power transmission between coaxes 24 and 28 is illustrated as maximum by sinusoidal graph 91, centered about line 95 which indicates average power between cables 24 and 28. At the same time, the line common to segments 30 and 32 is directly above conductor 18, lying in slot 13, so that the energy propagated between coaxial cables 25 and 28 is at the median or average value indicated by line 95. The sinusoidal variation of power between cables 25 and 28 is indicated by curve 92. Also at the time, T=0, the line common to segments 29 and 34 is directly above conductor 20, located in slot 15, so that the energy transferred between coax 27 and coax 28 is the median value, indicated by line 95 of FIGURE 2. Because conductor 19, situated in slot 14, is completely covered by segment 31 of disc 22, minimum energy transfer between coaxial cables 26 and 28 is effected, resulting in the minimum sinusoidal position of line 93 in FIGURE 2. It is noted that at any instant the sum of all the energy propagated from the various coaxial cables 24-27 to the common coax 28 is a constant equal to four times the value of the average power supplied to each transmission line, as indicated by line 95.

As disc 22 rotates, one-twelfth of a rotation, the conductor 17 goes from a fully unloaded condition to a condition wherein it coincides in position with the common intersection of segments 33 and 29. At this time, indicated by the abscissa vr/Z in FIGURE 2, the energy propagated between coaxial cables 28 and 24 is the average value as indicated by the intersection of graph 91 with line 95.

As disc 22 continues to rotate, conductor 17 becomes fully loaded by conducting segment 29 and minimum energy transfer between coaxes 24 and 28 is effected, as indicated by the intersection of sinusoidal curve 91 with the abscissa 11' and the line 96, FIGURE 2. As disc 22 continues to rotate through another of a revolution to the time 211', conductor 17 again becomes fully unloaded since segment 34 completely covers it, as indicated by the intersection of curve 91 with the maximum line 97 of FIGURE 2. As this sinusoidal variation in power transmitted between coax 2d and coax 28 occurs, a similar but out of phase transmission occurs in each of the other transmission lines to effect the power transmission variations indicated in FIGURE 2.

The power supplied through the variable coupler of FIGURE 1 is always a constant due to the symmetrical arrangement of each of the quarter wave length transmission lines about common point 16. Of course if the segments of disc 22 were not of equal area and geometric configuration, uneven power distribution in the various transmssion lines would occur. If it is not desirable to maintain power supplied between the common and parallel conductors equal, a non-symmetric arrangement of the transmission line or of the segmented disc may be effected. But for most applications, such as load switching of antennae array or conversion of a four horn amplitude monopulse antennae fed system to a conical scan system, it is desirable to maintain the power distribution equal in each of the transmission lines and to rotate the power transmitted between the parallel lines and the common lines at a constant velocity.

When the present invention is employed as a converter for a four horn amplitude monopulse radar antennae system to a conical scan system, the radar is connected to common coaxial cable 28 and the antenna horns are connected to cables 24-27, respectively. Due to the arrangement of conducting sectors 29, 3t 31 maximum and minimum energy transfer can occur between only one horn and the radar system. As the disc 22 rotates, the energy supplied between the radar and the horns is smoothly and cyclically varied and the composite antennae radiation pattern rotates in a conical scan.

Similarly, the invention is employed with an antenna pattern scanner by connecting the common terminal 16 to a transmitter and each of the plural terminals 17-21? to a separate antenna, each positioned on a different corner of a square tower. The power supplied to each antenna is modulated to cause the total pattern of the four antennae to scan or rotate about the tower as disc 22 turns.

Referring now to FIGURE 3 of the drawings, there is disclosed another embodiment of the present invention employing a pair of conical members 41 and 42, wherein member 41 is of such size as to fit within a hollow cone 42. A plurality of transmission line signal carrying conductors, only two of which are shown as 43 and 44, preferably of quarter wave length distance, extend on the exterior surface of metal, ground plane cone 41 between common point 45, at the cone apex, and points 4-6 and 4-7 at the cone base. Preferably the plural conductors 43 and 44 divide the solid angle formed at the cone apex into equal angles under which condition the conductors are considered symmetrically located about the cone apex. Quarter wave length conductors 43 and 44 are insulated from the conducting, ground plane surface of cone 41 by the air in the space therebetween. At the base of cone 41, wires 43 and 44 are respectively 6 connected to the interior conductor of coaxial cables 51 and 52. The exterior shields of cables 51, 52 and 53 are connected to the metallic cone 41 by suitable leads. Connection of the interior lead of coaxial cable 53 to the conductors 43 and 44 is effected through an aperture provided at the cone apex 45.

The conical member 41 together with the elements mounted and secured thereto are interiorly located with in hollow conical member 42 which is rotated at a predetermined speed by motor 36 under the control of reference generator 37. Provided on cone 42 is a plurality of conducting segmented areas, only two of which 54 and 55 are shown. A plurality of insulating segmented areas, only two of which 56 and 57 are shown, are interposed between the conducting areas.

The close spacing between the ground plane surface of cone 41 and the interior surface of cone 42 provides sufiicient electromagnetic coupling between the ground plane and the conducting segments 54 and 55 as to vary the distributed inductance and capacitance of the quarter wavelength segments.

As cone 42 is rotated by motor 36, conductors 43 and 44 which make up the quarter wave length transmission lines are varied from a fully shielded condition to a substantially two wire condition. In the former condition, wire 44 is covered by one of the conducting segments of cone 42, for example conducting segment 54, thereof while in the latter condition wire 44 is completely covered by one of the insulated portions 56 or 57. The relative spacing of the insulated and conducting segments of cone 42 with regard to the wires 43 and 44 is such that when the characteristic impedance of the quarter wave length transmission line between coaxes 52 and 53 is maximum the characteristic impedance of the quarter wave length transformer constituting wire 43 connected between coaxes 51 and 53 is minimum. As the conical member 42 is rotated these conditions are synchronously varied to provide a substantially sinusoidal variation in characteristic impedance of the transmission lines comprising wires 43 and 44 so that power coupled between common cable 53 and cables 51 and 52 is always constant.

As with FIGURE 1, each of the transmission lines between the common and parallel leads is maintained at substantially a quarter wave length because at this length variations in characteristic impedance have the greatest effect on the tranmission line input impedance while they have no effect on the reactance looking into the transmission line. Also, only one of the conducting segments 54 and 55 is coupled to wires 43 and 44 at a time due to the relative segment and wire spacing.

Referring now to FIGURE 4 of the drawing, there is disclosed an exploded view of still another embodiment of the invention. In this embodiment, a pair of coaxial cylinders 61 and 62 are provided. Cylinder 61 fits interiorly of hollow cylinder 62 and sufficiently close to the metallic ground plane wall 63 thereof to maintain the conducting strips on the exterior of cylinder 61, only two of which 64, 65 are shown, at the same potential as ground plane conductor 63 by electromagnetic coupling.

Five signal carrying conductors 66-70, preferably quarter wave length long, are axially mounted in slots 72-76 on the interior wall of metallic sleeve 63 but are insulated from sleeve 63 by air. Wires 66-70 are connected together to a common point 77 and to the interior conductor of coax 78, the shield of which is electrically connected to the ground plane metallic sleeve 63. The other end of conductors 66-70 are respectively connected to the interior conductor of coaxial cables 91-95, the outer shields of which are connected to the ground plane 63.

Cylinder 61 includes a plurality of axially extending conducting strips, two of which are shown as 64 and 65, between each of which extends an axially extending 7 insulated member, three of which are shown as 81, 82 and 83. The cylinder 61 is driven by motor referencegenerator set 37 at a constant rate of rotation so that the conducting strips 64 and 65 are synchronously brought into and out of coupling with the wires 66'7ti.

When one of the wires 66-7 is covered by one of the insulated segments 8183, a two wire transmission line is formed between the common terminal 77 and the respective coaxial cable 91-95. When one of the wires 66-70 is covered instead by a conducting segment, e.g. strip 64, a shielded transmission line is established between the common terminal 77 and the respective coaxial cable 91-95. In the tormer condition, each transmission line has maximum characteristic impedance, while in the .former state each line has minimum characteristic impedance. As cylinder 61 rotates through intermediate points between maximum and minimum, the characteristic impedance is smoothly varied.

The embodiment of FIGURE 4 is desirable because the chance of electromagnetic coupling between each of the wires 66-70 and more than one conducting strip is easily eliminated by merely spacing the wires and strips sufficiently. This is not true of the embodiments in FIGURES 1 and 3 where there is some coupling between all of the plural conducting strips and one transmission line signal carrying wire at the common point.

While the sketch of FIGURE 2 was described specifically in connection with the apparatus of FIGURE 1, it is to be understood the principles discussed therein are equally applicable to the embodiments illustrated in FIG- URES 3 and 4 and that the embodiments illustrated in FIGURES 3 and 4 function in exactly the same manner as that in FIGURE 1- and as illustrated in FIGURE 2 if they contain symmetrical components For most purposes it is desirable to employ a quarter wave length transmission line in each embodiment between the common and parallel conductors, because of the maximum impedance variation obtained therewith and the absence of reactance components in the transmission line characteristics. A long variable tapered section may be employed for in each transmission line if necessary to provide wide signal bandwidth or better matching between the common conductor and the plural conductors connected thereto. Frequency bandwidth may be increased in the present invention by employing a plurality of cascaded transmission line sections having different bandwidths which overlap.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

I claim:

1. A system for variably supplying RF. power between a plurality of terminals and a common terminal comprising a plurality of variable characteristic impedance transmission lines, said lines being separately connected between each of said plurality of terminals and said common terminal, a ground plane conductor common to all of said lines extending between said plurality of terminals and said common terminal, each of said lines including a signal carrying conductor electromagnetically coupled to said ground plane conductor and extending the length of its associated line in spaced relationship to said ground plane conductor, an electrically conductive member closely coupled to said ground plane conductor only by electromagnetic coupling, said signal carrying conductors being positioned between said ground plane conductor and said conductive elements, and means for moving said electrically conductive member transversely relative to the length of said signal carrying conductors to vary the electromagnetic coupling between said ground plane and signal carrying conductors.

2. The system of claim I wherein the length of each transmission line is substantially a quarter wave length at frequency of RF. signal coupled to said terminals.

3. A system for variably supplying RF. power between a plurality of separate terminals and a common terminal comprising a plurality of quarter wave length variable characteristic impedance transmission lines, said lines being separately connected between each of said terminals and said common terminal, a ground plane conductor common to all of said transmission lines, each of said transmission lines including a signal carrying conductor connected between one of said separate terminals and said common terminal and electromagnetically coupled to said ground plane conductor and extending in spaced relationship to said ground plane conductor, said signal carrying conductors being symmetrically disposed about said common terminal, an electrically conductive member closely coupled to said ground plane conductor only by electromagnetic coupling, said signal carrying conductors being positioned between said ground plane conductor and said conductive member, the maximum degree of electromagnetic coupling between said conductive member occurring with only one of said signal carrying conductors at a time, and means for moving said conductive member in sequential electromagnetic energy exchange relationship with each of said signal carrying conductors.

4. The system of claim 3 wherein said moving means rotates said conductive member relative to said signal carrying conductors about said common terminal at constant velocity.

5. The system of claim 4 wherein said ground plane conductor comprises an electrically conducting block hav ing a substantially planar surface with a plurality of flared slots extending symmetrically from a common point aligned with said common terminal, one of said conductors being positioned in each of said slots, and said conductive member including a plurality of wedge shaped conductive portions separated from each other by insulative portions, said conductive portions having a common apex coaxial with said common point and wherein said moving means rotates said conductive member about said common apex.

6. The system of claim 4 wherein said ground conductor comprises a cylindrical member, said conductors being equally spaced about said cylindrical member and extending axially thereof, said conductive member being an elongated strip mounted axially on another cylindrical member, said cylindrical members having a common axis aligned with said common terminal, and wherein said moving means rotates only one of said cylindrical members about said common axis.

7. The system of claim 4 wherein said ground plane conductor comprises a first conical member, said conductors being equally spaced about the apex of said first conical member and extending parallel to the surface thereof from the apex towards the base, a second conical member having its axial aligned with the axis of said first conical member, and said common terminal, said conductive member being a segment of said second conical member, and wherein said moving means rotates only one of said conical members about said axis.

8. A system for variably supplying RF. power between a plurality of separate terminals and a common terminal comprising a plurality of quarter wave length variable characteristic impedance transmission lines, said lines being separately connected between each of said terminals and said common terminal, a ground plane conductor common to all of said transmission lines, each of said transmission lines including a signal carrying conductor connected from one of said separate terminals to said common terminal and electromagnetically coupled to said ground plane conductor and extending in spaced relationship to said ground plane conductor, said signal carrying conductors being symmetrically disposed about said common terminal, a plurality of electrically conductive members closely coupled to said ground plane conductor only by electromagnetic coupling, said signal carrying conductors being positioned between said ground plane conductor and said conductive members, said conductive members being symmetrically arranged about said common terminal, the maximum degree of electromagnetic coupling between each of said conductive members occurring with only one of said signal carrying conductors at a time, and means for rotating said conductive members about said common terminal at constant velocity in sequential electromagnetic energy exchange relationship with each of said signal carrying conductors.

9. The system of claim 8 wherein said ground plane conductor comprises an electrically conducting block having a substantially planar surface with a plurality of flared slots extending symmetrically from a common point aligned with said common terminal, one of said conductors being positioned in each of said slots, and each of said conductive members being substantially wedge shaped, said wedge shaped conductive members being electrically insulated from each other and having a common apex coaxial with said common point, and wherein said moving means rotates said wedge shaped conductive members about said common apex.

10. The system of claim 8 wherein said ground plane conductor comprises a cylindrical member, said conductors being equally spaced about said cylindrical member and extending axially thereof, each of said conductive members being an elongated strip mounted axially on another cylindrical member, said strips being equally spaced about the surface of another cylindrical member, said cylindrical members having a common axis aligned with said common terminal, and wherein said moving means rotates only one of said cylindrical members about said common axis.

11. The system of claim 8 wherein said ground plane conductor comprises a first conical member, said conductors being equally spaced about the apex of said first conical member and extending parallel to the surface thereof from the apex towards the base, a second conical member having its axis aligned with the axis of said first conical member and said common terminal, said conductive members being equal area segments of said conical member, said segments being equally spaced about the surface of said second conical member and wherein said moving means rotates only one of said conical members about said axis.

12. A system for controlling the distribution of RF. signal power between a common electrical terminal and N separate electrical terminals, where N is an integer greater than 1, said system comprising N signal conductors, each of said signal conductors connecting a respective one of said N separate terminals to said common terminal, electrically conductive means spaced in partially shielding relation with each of said signal conductors, said signal conductors and said electrically conductive means forming N transmission lines, each of said transmission lines being substantially an odd number of quarter wavelengths long at the RF signal frequency, and means for sinusoidally varying the characteristic impedance of each of said transmission lines at a constant electrical phase relationship of 21r/N radians therebetween, said last named means including further electrically conductive means spaced from said signal conductors and movable at a constant velocity relative thereto for cyclically varying the amount by which said conductors are shielded.

13. The combination according to claim 12 wherein said signal conductors geometrically radiate from said common terminal in a fixed configuration having an axis of symmetry, said further electrically conductive means substantially conforming to said configuration, and wherein is further included means for rotating said further electrically conductive means about said axis of symmetry at a fixed mechanical frequency in cyclically varying electromagnetic coupling relation with each of said signal conductors.

14. The combination according to claim 13 wherein said further electrically conductive means includes a plurality of electrically conductive segments in said substantially conforming configuration, said conductive segments being symmetrically insulated from each other, to sinusoidally vary the R.F. signal power distribution between said common terminal and said N separate terminals at a frequency greater than said mechanical frequency of rotation.

References Cited by the Examiner UNITED STATES PATENTS 2,477,635 8/1949 Marchand 333-7 2,815,443 12/1957 Davis 328-104 2,879,483 3/1959 Montani 333-7 2,897,460 7/1959 La Rosa 33335 2,963,664 12/1960 Yeagley 333-35 HERMAN KARL SAALBACH, Primary Examiner,

ELI LIEBERMAN, Examiner, 

1. A SYSTEM FOR VARIABLY SUPPLYING R.F. POWER BETWEEN A PLURALITY OF TERMINALS AND A COMMON TERMINAL COMPRISING A PLURALITY OF VARIABLE CHARACTERISTIC IMPEDANCE TRANSMISSION LINES, SAID LINES BEING SEPARATELY CONNECTED BETWEEN EACH OF SAID PLURALITY OF TERMINALS AND SAID COMMON TERMINAL, A GROUND PLANE CONDUCTOR COMMON TO ALL OF SAID LINES EXTENDING BETWEEN SAID PLURALITY OF TERMINALS AND SAID COMMON TERMINAL, EACH OF SAID LINES INCLUDING A SIGNAL CARRYING CONDUCTOR ELECTROMAGNETICALLY COUPLED TO SAID GROUND PLANE CONDUCTOR AND EXTENDING THE LENGTH OF ITS ASSOCIATED LINE IN SPACED RELATIONSHIP TO SAID GROUND PLANE CONDUCTOR, AN ELECTRICALLY CONDUCTIVE MEMBER CLOSELY COUPLED TO SAID GROUND PLANE CONDUCTOR ONLY BY ELECTROMAGNETIC COUPLING, SAID SIGNAL CARRYING CONDUCTORS BEING POSITIONED BETWEEN SAID GROUND PLANE CONDUCTOR AND SAID CONDUCTIVE ELEMENTS, AND MEANS FOR MOVING SAID ELECTRICALLY CONDUCTIVE MEMBER TRANSVERSELY RELATIVE TO THE LENGTH OF SAID SIGNAL CARRYING CONDUCTORS TO VARY THE ELECTROMAGNETIC COUPLING BETWEEN SAID GROUND PLANE AND SIGNAL CARRYING CONDUCTORS. 